Table 1.
Clinical characteristics of the described genetically affected siblings
| Patient ID | 2042 | 2043 | 2044 |
|---|---|---|---|
| Gender | Female | Female | Female |
| Age at examination | 20 years | 18 years | 15 years |
| Age at onset | – | 8 months | 4 months |
| Initial sign / symptom | Hypertonia and hyperreflexia detected during the sampling session | Floppiness | Floppiness |
| Delayed motor development | – | + | + |
| Delayed speech | – | + | – |
| Epilepsy | – | + | – |
| Cognitive impairment | – | – | – |
| Degree of motor disability | No functional handicap but signs at examination | Walk with support / unable to run | Walk with support / unable to run |
| Muscle wasting (UL & LL) | – | – | – |
| UL hypertonia | – | – | – |
| UL motor deficit | – | – | – |
| UL hyperreflexia | + | + | + |
| LL hypertonia | + | + | + |
| LL motor deficit | – | Severe | Moderate |
| LL hyperreflexia | + | + | + |
| Sensory impairment | – | – | – |
| Dysarthria | – | + | + |
| Ocular cerebellar signs | – | + | + |
| Dysmetria | – | – | – |
| Optic atrophy | – | – | – |
| Clinical summary | Pyramidal features | Pyramidal features, seizures, delayed speech, ocular cerebellar signs and dysarthria | Pyramidal features, ocular cerebellar signs and dysarthria |
| MRI changes in brain and spinal cord | + | + | + |
| Serum lactate level in mmol/L (reference range 0.5–2.2 mmol/L) | 6.13 | 6.8 | 5.97 |
UL upper limb, LL lower limb, − absent, + present